The present invention is directed to a portable, battery powered device used to supply or deliver oxygen to a patient or user. Known devices and systems provide a continuous flow of oxygen from a regulated oxygen source. For example, a pressurized container of oxygen includes an adjustable valve that provides a continuous flow of oxygen gas to the patient. The flow rate can be adjusted but, once set, the system is intended to provide a continuous flow.
A patient, of course, does not continuously inhale so that a portion of the oxygen provided under a continuous flow system is not actually used by the patient. Other manufacturers, therefore, have developed oxygen conserving devices that provide a pulse or dose of oxygen. For example, the following U.S. patents are generally related to these types of structures: U.S. Pat. Nos. 3,923,056; 4,462,398; 4,570,631; 4,706,664; 4,823,788; 4,873,971; 4,932,402; 5,005,570; 5,038,770; and 5,315,990. Many of these alternative arrangements are simply too complex, expensive, or inadequate so that a need exists for a simple, economical, and effective device that controls oxygen supply to a user, and that allows the user to easily convert the device from a pulse mode operation to a continuous flow mode without difficulty or attendant complexity or cost associated with the device.